| Encode::Supported -- Encodings supported by Encode |
Encode::Supported -- Encodings supported by Encode
Encoding names are case insensitive. White space in names is ignored. In addition, an encoding may have aliases. Each encoding has one ``canonical'' name. The ``canonical'' name is chosen from the names of the encoding by picking the first in the following sequence (with a few exceptions).
In case de jure canonical names differ from that of the Encode module, they are always aliased if it ever be implemented. So you can safely tell if a given encoding is implemented or not just by passing the canonical name.
Because of all the alias issues, and because in the general case encodings have state, ``Encode'' uses an encoding object internally once an operation is in progress.
As of Perl 5.8.0, at least the following encodings are recognized. Note that unless otherwise specified, they are all case insensitive (via alias) and all occurrence of spaces are replaced with '-'. In other words, ``ISO 8859 1'' and ``iso-8859-1'' are identical.
Encodings are categorized and implemented in several different modules
but you don't have to use Encode::XX to make them available for
most cases. Encode.pm will automatically load those modules on demand.
The following encodings are always available.
Canonical Aliases Comments & References ---------------------------------------------------------------- ascii US-ascii ISO-646-US [ECMA] ascii-ctrl Special Encoding iso-8859-1 latin1 [ISO] null Special Encoding utf8 UTF-8 [RFC2279] ----------------------------------------------------------------
null and ascii-ctrl are special. ``null'' fails for all character so when you set fallback mode to PERLQQ, HTMLCREF or XMLCREF, ALL CHARACTERS will fall back to character references. Ditto for ``ascii-ctrl'' except for control characters. For fallback modes, see the Encode manpage.
Unicode coding schemes other than native utf8 are supported by Encode::Unicode, which will be autoloaded on demand.
---------------------------------------------------------------- UCS-2BE UCS-2, iso-10646-1 [IANA, UC] UCS-2LE [UC] UTF-16 [UC] UTF-16BE [UC] UTF-16LE [UC] UTF-32 [UC] UTF-32BE UCS-4 [UC] UTF-32LE [UC] UTF-7 [RFC2152] ----------------------------------------------------------------
To find how (UCS-2|UTF-(16|32))(LE|BE)? differ from one another, see the Encode::Unicode manpage.
UTF-7 is a special encoding which ``re-encodes'' UTF-16BE into a 7-bit encoding. It is implemented separately by Encode::Unicode::UTF7.
Encode::Byte implements most single-byte encodings except for Symbols and EBCDIC. The following encodings are based on single-byte encodings implemented as extended ASCII. Most of them map \x80-\xff (upper half) to non-ASCII characters.
Lang/Regions ISO/Other Std. DOS Windows Macintosh Others
----------------------------------------------------------------
N. America (ASCII) cp437 AdobeStandardEncoding
cp863 (DOSCanadaF)
W. Europe iso-8859-1 cp850 cp1252 MacRoman nextstep
hp-roman8
cp860 (DOSPortuguese)
Cntrl. Europe iso-8859-2 cp852 cp1250 MacCentralEurRoman
MacCroatian
MacRomanian
MacRumanian
Latin3[1] iso-8859-3
Latin4[2] iso-8859-4
Cyrillics iso-8859-5 cp855 cp1251 MacCyrillic
(See also next section) cp866 MacUkrainian
Arabic iso-8859-6 cp864 cp1256 MacArabic
cp1006 MacFarsi
Greek iso-8859-7 cp737 cp1253 MacGreek
cp869 (DOSGreek2)
Hebrew iso-8859-8 cp862 cp1255 MacHebrew
Turkish iso-8859-9 cp857 cp1254 MacTurkish
Nordics iso-8859-10 cp865
cp861 MacIcelandic
MacSami
Thai iso-8859-11[3] cp874 MacThai
(iso-8859-12 is nonexistent. Reserved for Indics?)
Baltics iso-8859-13 cp775 cp1257
Celtics iso-8859-14
Latin9 [4] iso-8859-15
Latin10 iso-8859-16
Vietnamese viscii cp1258 MacVietnamese
----------------------------------------------------------------
[1] Esperanto, Maltese, and Turkish. Turkish is now on 8859-9.
[2] Baltics. Now on 8859-10, except for Latvian.
[3] TIS 620 + Non-Breaking Space (0xA0 / U+00A0)
[4] Nicknamed Latin0; the Euro sign as well as French and Finnish
letters that are missing from 8859-1 were added.
All cp* are also available as ibm-*, ms-*, and windows-* . See also http://czyborra.com/charsets/codepages.html.
Macintosh encodings don't seem to be registered in such entities as IANA. ``Canonical'' names in Encode are based upon Apple's Tech Note 1150. See http://developer.apple.com/technotes/tn/tn1150.html for details.
---------------------------------------------------------------- koi8-f koi8-r cp878 [RFC1489] koi8-u [RFC2319] ----------------------------------------------------------------
GSM0338 is for GSM handsets. Though it shares alphanumerals with ASCII, control character ranges and other parts are mapped very differently, mainly to store Greek characters. There are also escape sequences (starting with 0x1B) to cover e.g. the Euro sign.
This was once handled by the Encode::Bytes manpage but because of all those unusual specifications, Encode 2.20 has relocated the support to the Encode::GSM0338 manpage. See the Encode::GSM0338 manpage for details.
decode() will return an empty string for them.
One possible workaround is
$gsm =~ s/\x00\z/\x00\x00/;
$uni = decode("gsm0338", $gsm);
$uni .= "\xA0" if $gsm =~ /\x1B\z/;
Note that the Encode implementation of GSM0338 does not implement the reuse of Latin capital letters as Greek capital letters (for example, the 0x5A is U+005A (LATIN CAPITAL LETTER Z), not U+0396 (GREEK CAPITAL LETTER ZETA).
The GSM0338 is also covered in Encode::Byte even though it is not an ``extended ASCII'' encoding.
Note that Vietnamese is listed above. Also read ``Encoding vs Charset'' below. Also note that these are implemented in distinct modules by countries, due to the size concerns (simplified Chinese is mapped to 'CN', continental China, while traditional Chinese is mapped to 'TW', Taiwan). Please refer to their respective documentation pages.
Standard DOS/Win Macintosh Comment/Reference
----------------------------------------------------------------
euc-cn [1] MacChineseSimp
(gbk) cp936 [2]
gb12345-raw { GB12345 without CES }
gb2312-raw { GB2312 without CES }
hz
iso-ir-165
----------------------------------------------------------------
[1] GB2312 is aliased to this. See L<Microsoft-related naming mess> [2] gbk is aliased to this. See L<Microsoft-related naming mess>
Standard DOS/Win Macintosh Comment/Reference
----------------------------------------------------------------
euc-jp
shiftjis cp932 macJapanese
7bit-jis
iso-2022-jp [RFC1468]
iso-2022-jp-1 [RFC2237]
jis0201-raw { JIS X 0201 (roman + halfwidth kana) without CES }
jis0208-raw { JIS X 0208 (Kanji + fullwidth kana) without CES }
jis0212-raw { JIS X 0212 (Extended Kanji) without CES }
----------------------------------------------------------------
Standard DOS/Win Macintosh Comment/Reference
----------------------------------------------------------------
euc-kr MacKorean [RFC1557]
cp949 [1]
iso-2022-kr [RFC1557]
johab [KS X 1001:1998, Annex 3]
ksc5601-raw { KSC5601 without CES }
----------------------------------------------------------------
[1] ks_c_5601-1987, (x-)?windows-949, and uhc are aliased to this. See below.
Standard DOS/Win Macintosh Comment/Reference
----------------------------------------------------------------
big5-eten cp950 MacChineseTrad {big5 aliased to big5-eten}
big5-hkscs
----------------------------------------------------------------
Standard DOS/Win Macintosh Comment/Reference ---------------------------------------------------------------- big5ext CMEX's Big5e Extension big5plus CMEX's Big5+ Extension cccii Chinese Character Code for Information Interchange euc-tw EUC (Extended Unix Character) gb18030 GBK with Traditional Characters ----------------------------------------------------------------
Standard DOS/Win Macintosh Comment/Reference ---------------------------------------------------------------- euc-jisx0213 shiftjisx0123 iso-2022-jp-3 jis0213-1-raw jis0213-2-raw ----------------------------------------------------------------
---------------------------------------------------------------- cp37 cp500 cp875 cp1026 cp1047 posix-bc ----------------------------------------------------------------
---------------------------------------------------------------- symbol dingbats MacDingbats AdobeZdingbat AdobeSymbol ----------------------------------------------------------------
---------------------------------------------------------------- MIME-Header [RFC2047] MIME-B [RFC2047] MIME-Q [RFC2047] ----------------------------------------------------------------
The following encodings are not supported as yet; some because they are rarely used, some because of technical difficulties. They may be supported by external modules via CPAN in the future, however.
encode() (because it includes JIS X 0208/0212, KSC5601, and
GB2312 simultaneously, whose code points in Unicode overlap. So you
need to lookup the database to determine to what character set a given
Unicode character should belong).
'8' - arabic8, greek8, hebrew8, kana8, thai8, and turkish8 '15' - japanese15, korean15, and roi15
MacArmenian, MacBengali, MacBurmese, MacEthiopic MacExtArabic, MacGeorgian, MacKannada, MacKhmer MacLaotian, MacMalayalam, MacMongolian, MacOriya MacSinhalese, MacTamil, MacTelugu, MacTibetan MacVietnamese
The rest which are already available are based upon the vendor mappings at http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/ .
MacDevanagari MacGurmukhi MacGujarati
For details, please see Unicode mapping issues and notes: at
http://www.unicode.org/Public/MAPPINGS/VENDORS/APPLE/DEVANAGA.TXT .
I believe this issue is prevalent not only for Mac Indics but also in other Indic encodings, but the above were the only Indic encodings maps that I could find at http://www.unicode.org/ .
We are used to using the term (character) encoding and character set interchangeably. But just as confusing the terms byte and character is dangerous and the terms should be differentiated when needed, we need to differentiate encoding and character set.
To understand that, here is a description of how we make computers grok our characters.
A character encoding scheme (CES) determines how to encode a given character set, or a set of multiple character sets. 7bit ISO-2022 is an example of a CES. You switch between character sets via escape sequences.
Technically, or mathematically, speaking, a character set encoded in such a CES that maps character by character may form a CCS. EUC is such an example. The CES of EUC is as follows:
By carefully looking at the encoded byte sequence, you can find that the byte sequence conforms a unique number. In that sense, EUC is a CCS generated by a CES above from up to four CCS (complicated?). UTF-8 falls into this category. See perlUnicode/``UTF-8'' to find out how UTF-8 maps Unicode to a byte sequence.
You may also have found out by now why 7bit ISO-2022 cannot comprise a CCS. If you look at a byte sequence \x21\x21, you can't tell if it is two !'s or IDEOGRAPHIC SPACE. EUC maps the latter to \xA1\xA1 so you have no trouble differentiating between ``!!''. and `` ''.
This section tries to classify the supported encodings by their applicability for information exchange over the Internet and to choose the most suitable aliases to name them in the context of such communication.
(**), you need
Encode::HanExtra, available from CPAN.
Encoding names
US-ASCII UTF-8 ISO-8859-* KOI8-R Shift_JIS EUC-JP ISO-2022-JP ISO-2022-JP-1 EUC-KR Big5 GB2312
are registered with IANA as preferred MIME names and may be used over the Internet.
Shift_JIS has been officialized by JIS X 0208:1997.
Microsoft-related naming mess gives details.
GB2312 is the IANA name for EUC-CN.
See Microsoft-related naming mess for details.
GB_2312-80 raw encoding is available as gb2312-raw
with Encode. See the Encode::CN manpage for details.
EUC-CN KOI8-U [RFC2319]
have not been registered with IANA (as of March 2002) but
seem to be supported by major web browsers.
The IANA name for EUC-CN is GB2312.
KS_C_5601-1987
is heavily misused. See Microsoft-related naming mess for details.
KS_C_5601-1987 raw encoding is available as kcs5601-raw
with Encode. See the Encode::KR manpage for details.
UTF-16 UTF-16BE UTF-16LE
are IANA-registered charsets. See [RFC 2781] for details.
Jungshik Shin reports that UTF-16 with a BOM is well accepted
by MS IE 5/6 and NS 4/6. Beware however that
UTF-16 support in any software you're going to be
using/interoperating with has probably been less tested
then UTF-8 support
UTF-8 coded data seamlessly passes traditional
command piping (cat, more, etc.) while UTF-16 coded
data is likely to cause confusion (with its zero bytes,
for example)
it is beyond the power of words to describe the way HTML browsers
encode non-ASCII form data. To get a general impression, visit
http://www.alanflavell.org.uk/charset/form-i18n.html.
While encoding of form data has stabilized for UTF-8 encoded pages
(at least IE 5/6, NS 6, and Opera 6 behave consistently), be sure to
expect fun (and cross-browser discrepancies) with UTF-16 encoded
pages!
The rule of thumb is to use UTF-8 unless you know what
you're doing and unless you really benefit from using UTF-16.
ISO-IR-165 [RFC1345] VISCII GB 12345 GB 18030 (**) (see links below) EUC-TW (**)
are totally valid encodings but not registered at IANA. The names under which they are listed here are probably the most widely-known names for these encodings and are recommended names.
BIG5PLUS (**)
is a proprietary name.
Microsoft products misuse the following names:
EUC-KR.
Proper names: CP949, UHC, x-windows-949 (as used by Mozilla).
See http://lists.w3.org/Archives/Public/ietf-charsets/2001AprJun/0033.html for details.
Encode aliases KS_C_5601-1987 to cp949 to reflect this common
misusage. Raw KS_C_5601-1987 encoding is available as
kcs5601-raw.
See the Encode::KR manpage for details.
EUC-CN.
Proper names: CP936, GBK.
GB2312 has been registered in the EUC-CN meaning at
IANA. This has partially repaired the situation: Microsoft's
GB2312 has become a superset of the official GB2312.
Encode aliases GB2312 to euc-cn in full agreement with
IANA registration. cp936 is supported separately.
Raw GB_2312-80 encoding is available as gb2312-raw.
See the Encode::CN manpage for details.
Big5.
Proper name: CP950.
Encode separately supports Big5 and cp950.
Shift_JIS.
JIS has not endorsed the full Microsoft standard however.
The official Shift_JIS includes only JIS X 0201 and JIS X 0208
character sets, while Microsoft has always used Shift_JIS
to encode a wider character repertoire. See IANA registration for
Windows-31J.
As a historical predecessor, Microsoft's variant probably has more rights for the name, though it may be objected that Microsoft shouldn't have used JIS as part of the name in the first place.
Unambiguous name: CP932. IANA name (also used by Mozilla, and
provided as an alias by Encode): Windows-31J.
Encode separately supports Shift_JIS and cp932.
encoding, CES.
While the word combination character set has lost this meaning
in MIME context since [RFC 2130], the charset abbreviation has
retained it. This is how [RFC 2277] and [RFC 2278] bless charset:
This document uses the term "charset" to mean a set of rules for mapping from a sequence of octets to a sequence of characters, such as the combination of a coded character set and a character encoding scheme; this is also what is used as an identifier in MIME "charset=" parameters, and registered in the IANA charset registry ... (Note that this is NOT a term used by other standards bodies, such as ISO). [RFC 2277]
The 7 bit version switches character set via escape sequence so it cannot form a CCS. Since this is more difficult to handle in programs than the 8 bit version, the 7 bit version is not very popular except for iso-2022-jp, the de facto standard CES for e-mails.
The 8 bit version can form a CCS. EUC and ISO-8859 are two examples thereof. Pre-5.6 perl could use them as string literals.
the Encode manpage, the Encode::Byte manpage, the Encode::CN manpage, the Encode::JP manpage, the Encode::KR manpage, the Encode::TW manpage, the Encode::EBCDIC manpage, the Encode::Symbol manpage the Encode::MIME::Header manpage, the Encode::Guess manpage
ISO-2022)The specification of ISO-2022 is available from the link above.
Most of the canonical names in Encode derive from this list
so you can directly apply the string you have extracted from MIME
header of mails and web pages.
The glossary of this document is based upon this site.
Contains a lot of useful information, especially gory details of ISO vs. vendor mappings.
Somewhat obsolete (last update in 1996), but still useful. Also try
ftp://ftp.oreilly.com/pub/examples/nutshell/cjkv/pdf/GB18030_Summary.pdf
You will find brief info on EUC-CN, GBK and mostly on GB 18030.
And especially its subject 8.
A comprehensive overview of the Korean (KS *) standards.
CJKV Information Processing by Ken LundeThe modern successor of CJK.inf.
Features a comprehensive coverage of CJKV character sets and encodings along with many other issues faced by anyone trying to better support CJKV languages/scripts in all the areas of information processing.
To purchase this book, visit http://oreilly.com/catalog/9780596514471/ or your favourite bookstore.
| Encode::Supported -- Encodings supported by Encode |